Conducting nanofibres of solvatofluorochromic cyclohexanetrione-dithiolylidene-based C3 symmetric molecule

We report a novel set of easily tailorable C₃ symmetric molecules with a π-extended core and adorned with different thioalkyl groups, exhibiting solvatofluorochromic and amphoteric redox behaviour. The nearly planar core exhibits intermolecular face-to-face π-stacking, SS and intramolecular SO interactions. Current-sensing atomic force microscopy studies revealed a high conductivity of ∼0.15 mS cm^-1 in the undoped J-aggregate nanofibres of the thiopropyl appended gelator.

Mixed-Stack Charge Transfer Crystals of Pillar[5]quinone and Tetrathiafulvalene Exhibiting Ferroelectric Features

Ferroelectric materials find extensive applications in the fabrication of compact memory devices and ultra-sensitive multifunctional detectors. Face-to-face alternate stacking of electron donors and acceptors effectuate long-range unidirectional ordering of charge-transfer (CT) dipoles, promising tunable ferroelectricity. Herein we report a new TTF-quinone system-an emerald green CT complex consisting pillar[5]quinone (P5Q) and tetrathiafulvalene (TTF). The CT crystals, as determined by single crystal synchrotron X-ray diffraction, adopt a 1:1 mixed-stack arrangement of donor and acceptor with alternating dimers of TTF and 1,4-dioxane encapsulated P5Q. The TTF-P5Q.dioxane crystal possesses a macroscopic polarization axis giving rise to ferroelectricity at room temperature. The CT complex manifests ferroelectric features such as optical polarization rotation, temperature-dependent phase transition and piezoelectric response in single crystals. Ferroelectric behavior observed in P5Q-based CT complex widens the scope for further work on this structurally intriguing and readily accessible cyclic pentaquinone.

Cascade energy transfer and tunable emission from nanosheet hybrids: locating acceptor molecules through chiral doping

A donor–acceptor–donor triad with excellent intramolecular energy transfer (99%) exhibits cascade energy transfer in the presence of second acceptors leading to tunable emission colours. Chiral acceptor doping enables chiral induction and to locate acceptors in the donor scaffold.

Counteranion Driven Homochiral Assembly of a Cationic C3-Symmetric Gelator through Ion-Pair Assisted Hydrogen Bond

The helical handedness in achiral self-assemblies is mostly complex due to spontaneous symmetry breaking or kinetically controlled random assembly formation. Here an attempt has been made to address this issue through chiral anion exchange. A new class of cationic achiral C3-symmetric gelator devoid of any conventional gelation assisting functional units is found to form both right- and left-handed helical structures. A chiral counteranion exchange-assisted approach is successfully introduced to control the chirality sign and thereby to obtain preferred homochiral assemblies. Formation of anion-assisted chiral assembly was confirmed by circular dichroism (CD) spectroscopy, microscopic images, and crystal structure. The X-ray crystal structure reveals the construction of helical assemblies with opposite handedness for (+)- and (-)-chiral anion reformed gelators. The appropriate counteranion driven ion-pair-assisted hydrogen-bonding interactions are found responsible for the helical bias control in this C3-symmetric gelator.

Hydrogel-Derived Soft Materials for Biomimetic and Energy-Related Functions

Supramolecular assembly of molecules leading to gelation of large amount of solvents is always a fascinating topic of research. In the very recent past, the exciting developments have marked hydrogels as intriguing materials with excellent features. Hydrogel scaffolds enable the accommodation of organic and/or inorganic guest materials to deliver diverse applications. Hydrogels have been exploited to generate soft materials with mechanical anisotropy, tunable rigidity, self-healing properties, as well as photocatalytic capabilities towards H2 production. Remarkably, the combination of a photocatalyst and a light-harvesting system in the gel matrix provides a unique means to photocatalytic H2 production. The biomimetic applications of hydrogels have also generated much attraction due to their potential demonstrations. The diverse applications underline the significance of such a soft gel medium to reach the final goal. Herein, important reports pertaining to the use of hydrogels as an effective way to generate advanced materials for biomimetic and energy-related issues are discussed.

Self-assembled vesicles of urea-tethered foldamers as hydrophobic drug carriers

Nonamphiphilic α,β-hybrid foldamers form hollow vesicular architectures which can take up and release the anticancer hydrophobic drug curcumin.

Seeded on-surface supramolecular growth for large area conductive donor–acceptor assembly

A seeded, on-surface, supramolecular growth leads to large area conductive donor–acceptor assembly via evaporation-assisted growth from active termini of solution-formed sheaf-like seeds.

Paradigms shift when solvent-less fluids come into play

A new phase of material that challenges the established paradigms.

Nonvolatile liquid anthracenes for facile full-colour luminescence tuning at single blue-light excitation

Nonvolatile room-temperature luminescent molecular liquids are a new generation of organic soft materials. They possess high stability, versatile optical properties, solvent-free fluid behaviour and can effectively accommodate dopant dye molecules. Here we introduce an approach to optimize anthracene-based liquid materials, focussing on enhanced stability, fluorescence quantum yield, colour tunability and processability, with a view to flexible electronic applications. Enveloping the anthracene core in low-viscosity branched aliphatic chains results in stable, nonvolatile, emissive liquid materials. Up to 96% efficient energy-transfer-assisted tunable emission is achieved by doping a minute amount of acceptor dye in the solvent-free state. Furthermore, we use a thermoresponsive dopant to impart thermally controllable luminescence colours. The introduced strategy leading to diverse luminescence colours at a single blue-light excitation can be an innovative replacement for currently used luminescent materials, providing useful continuous emissive layers in developing foldable devices.

Elastic constants of Ultrasonic Additive Manufactured Al 3003-H18

Ultrasonic Additive Manufacturing (UAM), also known as Ultrasonic Consolidation (UC), is a layered manufacturing process in which thin metal foils are ultrasonically bonded to a previously bonded foil substrate to create a net part. Optimization of process variables (amplitude, normal load and velocity) is done to minimize voids along the bonded interfaces. This work pertains to the evaluation of bonds in UAM builds through ultrasonic testing of a build's elastic constants. Results from ultrasonic testing on UAM parts indicate orthotropic material symmetry and a reduction of up to 48% in elastic constant values compared to a control sample. The reduction in elastic constant values is attributed to interfacial voids. In addition, the elastic constants in the plane of the Al foils have nearly the same value, while the constants normal to the foil direction have much different values. In contrast, measurements from builds made with Very High Power Ultrasonic Additive Manufacturing (VHP UAM) show a drastic improvement in elastic properties, approaching values similar to that of bulk aluminum.

Solvent-free luminescent organic liquids

Illuminating! Isolation of a π-core by covalently attached flexible hydrocarbon chains has been employed to synthesize blue-emitting oligo(p-phenylenevinylene) (OPV) liquids with tunable viscosity and optical properties. A solvent-free, stable, white-light emitting ink/paint, which can be applied onto various surfaces and even onto LEDs, was made by blending of liquid OPVs with emissive solid dopants.

Self-assembled gelators for organic electronics

Nature excels at engineering materials by using the principles of chemical synthesis and molecular self-assembly with the help of noncovalent forces. Learning from these phenomena, scientists have been able to create a variety of self-assembled artificial materials of different size, shapes, and properties for wide ranging applications. An area of great interest in this regard is solvent-assisted gel formation with functional organic molecules, thus leading to one-dimensional fibers. Such fibers have improved electronic properties and are potential soft materials for organic electronic devices, particularly in bulk heterojunction solar cells. Described herein is how molecular self-assembly, which was originally proposed as a simple laboratory curiosity, has helped the evolution of a variety of soft functional materials useful for advanced electronic devices such as organic field-effect transistors and organic solar cells. Highlights on some of the recent developments are discussed.